The present invention relates to a process for oxidizing organic compounds using an oxidant over an oxidizing catalyst under catalytic distillation conditions. More particularly, the present invention relates to hydroxylating saturated or unsaturated, aliphatic compounds using an oxidizing gas over a molecular sieve catalyst under catalytic distillation conditions.
Various methods are known to produce hydroxylated organic compounds. The majority of such processes require multiple steps to produce a hydroxylated product and many require expensive and/or sensitive catalysts. Direct hydroxylation of organic compounds theoretically should be more cost effective than conventional multi-step processes.
Raja and Thomas, Chem. Commun. 1999, pp. 1841-1842, have reported that dodecane can be partially oxidized with oxygen in an autoclave to produce dodecanol and a variety of oxygenated products. In the reported process, selectivity to dodecanol was about 35%. Because of the existence of a variety of oxygenated products, the separation of the dodecanol from the oxygenated products will be difficult even with an additional separation step.
In addition, the reaction of organics and oxidants can be highly exothermic. Expensive, complex system designs may be required to handle the excess heat. The expense of such reactions is further increased by coke formation from the decomposition products formed at such high temperatures. In addition, the coked catalyst must be regenerated at frequent intervals.
Hydroxylated organic compounds of commercial importance are alcohols of saturated or unsaturated, aliphatic compounds. Alcohols of these compounds are used in making detergents, soaps, surfactants, and freeze point depressants in lubricating oils. These alcohols currently are produced using relatively complex commercial processes, such as by oxo or hydroformylation of long chain olefins. Additional routes to make these alcohols are dehydrohalogenation of alkyl halides.
More economical and efficient processes are needed for directly hydroxylating saturated or unsaturated, aliphatic compounds.
The present invention provides a process comprising:
continuously contacting, in a distillation column reactor comprising a reaction zone and a distillation zone, at least one, saturated or unsaturated, aliphatic compound having carbon atoms in the range of 6 to 30 with an oxidation catalyst and an oxidant under conditions effective to hydroxylate said aliphatic compound thereby producing a hydroxylated product, while maintaining at least a portion of said aliphatic compound in a liquid phase;
continuously separating said hydroxylated product from the un-reacted aliphatic compound in the distillation zone under conditions effective to vaporize said un-reacted aliphatic compound and maintain said hydroxylated product in a liquid phase; and
recovering the said separated hydroxylated product from the distillation column reactor.